The New York Public Library used funds raised by selling artworks, including Asher B. Durand’s “Kindred Spirits,” to purchase the papers of the historian Arthur M. Schlesinger Jr., who died in February.

The library announced its acquisition of Schlesinger’s papers on Monday, without disclosing the price. A spokeswoman for the library, Gayle Snible, said the funds came out of an endowment established from the sale in 2005 of 19 artworks owned by the library, including “Kindred Spirits.” The endowment provides an additional $2.5 million annually for acquisitions.

The Wal-Mart heiress Alice Walton, who is building a museum in Bentonville, Ark., to be called Crystal Bridges Museum of American Art, purchased “Kindred Spirits” from the library for $35 million. The sale was conducted by silent auction, with the parties submitting sealed bids. Some critics, unhappy about the painting leaving New York, argued at the time that the secretive process favored parties like Ms. Walton, who could afford to overpay by millions of dollars, over New York institutions like the Metropolitan Museum of Art, which in a partnership with the National Gallery of Art in Washington submitted a much lower bid.

One source suggested that the library itself may have overpaid for the Schlesinger papers. A senior library official at an Ivy League university, who asked not to be identified by name, said that he was contacted in recent years about the papers by a representative for Schlesinger, but that the asking price, which he recalled as “in the high six figures or low seven figures,” was too high.

“These are largely the papers of an academic — although he was obviously a public intellectual and well known,” the official said. “What they were asking was way out of line with what they were worth.”

Such a collection would generally be appraised on the basis of how many presidential letters it included, since these are sought after by autograph collectors, the library official explained. That financial value doesn’t automatically translate into intellectual value, however. Such letters may be largely social, such as “Jack Kennedy saying, ‘I’m glad you were able to come to our party today,'” the official added.

Many of Schlesinger’s papers from the period between 1940 and 1965, when he was a professor at Harvard, Special Assistant to President Kennedy, and an author, belong to the John F. Kennedy Presidential Library and Museum in Boston. These include his incoming correspondence for that whole period, as well as carbon copies of his outgoing letters between 1961 and 1965; his White House Diary; telephone logs; a file on speeches he delivered; a file on classified subjects, and background material and manuscripts for his book on the Kennedy administration, “A Thousand Days.” The papers the library acquired comprise over 300 linear feet of correspondence, journals, manuscripts of writings, research files, phone logs, sound recordings, date books, and clippings, according to the press release put out by the library.

The agent Andrew Wylie, who negotiated the deal (in collaboration with William vanden Heuvel, who advised the family), said that the papers’ value derived from “the enduring quality of Arthur’s mind and his grace as a literary stylist. He’s a significant American historian,” Mr. Wylie continued, “and there are not that many.”